Carbon dioxide electrolytic device and method of electrolyzing carbon dioxide

Abstract

A carbon dioxide electrolytic device of an embodiment includes: an electrolysis cell including a cathode, an anode, a carbon dioxide supply flow path, solution supply flow paths, and a separator; a rinse solution source which supplies a rinse solution to at least one of the solution supply flow paths and the carbon dioxide supply flow path; a first electric conductivity meter provided on a discharge port side from the electrolysis cell of at least one of the solution supply flow paths and the carbon dioxide supply flow path; and a rinse solution supply controller which controls stop operation of the rinse solution source according to a measurement result of the first electric conductivity meter.

What is claimed is: 
     
         1 . A carbon dioxide electrolytic device, comprising:
 an electrolysis cell including a cathode to reduce carbon dioxide and thus produce a carbon compound, an anode to oxidize water and thus produce oxygen, a carbon dioxide supply flow pass to supply carbon dioxide so as to be brought into contact with the cathode, a solution supply flow path to supply an electrolytic solution so as to be brought into contact with at least the anode among the cathode and the anode, and a separator separating the anode and the cathode;   a rinse solution source configured to supply a rinse solution to at least one of the solution supply flow path and the carbon dioxide supply flow path of the electrolysis cell;   a first electric conductivity meter provided on a discharge port side from the electrolysis cell of at least one of the solution supply flow path and the carbon dioxide supply flow path; and   a rinse solution supply controller configured to control stop operation of the rinse solution source according to a measurement result of the first electric conductivity meter.   
     
     
         2 . The device according to  claim 1 , wherein:
 the electric conductivity meter is controlled so as to measure an electric conductivity of the rinse solution at any time during the supply of the rinse solution; and   the rinse solution source is controlled by the rinse solution supply controller so as to stop the supply of the rinse solution when at least one of an electric conductivity of the rinse solution and a time change in the electric conductivity is equal to or less than a request criterion.   
     
     
         3 . The device according to  claim 1 , further comprising
 a second electric conductivity meter provided on an inflow port side to the electrolysis cell of at least one of the solution supply flow path and the carbon dioxide supply flow path, wherein   the rinse solution source is controlled by the rinse solution supply controller so as to stop the supply of the rinse solution when a difference between an electric conductivity of the rinse solution measured by the second electric conductivity meter and an electric conductivity of the rinse solution measured by the first electric conductivity meter is equal to or less than a request criterion.   
     
     
         4 . The device according to  claim 1 , further comprising:
 a reduction performance detection unit configured to collect reduction performance data including at least one selected from a cell voltage, a cell current, a cathode potential, and an anode potential of the electrolysis cell, a production amount of a reduction product caused by the reduction electrode, and a product proportion in the reduction product; and   an electrolysis operation controller configured to control operation of the electrolysis cell based on the reduction performance data.   
     
     
         5 . The device according to  claim 1 , further comprising:
 an electrolytic solution concentration meter to measure a concentration of the electrolytic solution in the solution supply flow path which supplies the electrolytic solution to the anode; and a flow rate meter to measure a gas flow rate in the carbon dioxide supply flow path.   
     
     
         6 . The device according to  claim 5 , further comprising
 an electrolysis operation controller configured to control the electrolysis cell so as to stop operation of the electrolysis cell when a time integral value of a product of the concentration of the electrolytic solution and the gas flow rate from a reference time is equal to or less than a request criterion, the reference time being the one shorter between elapsed times from after starting a device start-up and from after stopping previous refresh operation, wherein   the rinse solution supply controller controls the rinse solution source so as to start supply of the rinse solution after the operation stop of the electrolysis cell.   
     
     
         7 . The device according to  claim 1 , further comprising
 an alternating-current resistance meter which measures an impedance of the electrolysis cell.   
     
     
         8 . The device according to  claim 7 , further comprising
 an electrolysis operation controller configured to control the electrolysis cell so as to stop operation of the electrolysis cell when the impedance is equal to or less than a request criterion, wherein   the rinse solution supply controller controls the rinse solution source so as to start supply of the rinse solution after the operation stop of the electrolysis cell.   
     
     
         9 . A method for electrolyzing carbon dioxide, comprising:
 supplying carbon dioxide to a carbon dioxide supply flow path in an electrolysis cell, and supplying an electrolytic solution to a solution supply flow path in the electrolysis cell, the electrolysis cell having an anode, a cathode, the carbon dioxide supply flow path which supplies the carbon dioxide to the cathode, and the solution supply flow path which supplies the electrolytic solution to at least the anode among the cathode and the anode;   supplying a current from a power supply connected to the anode and the cathode, to reduce carbon dioxide and thus produce a carbon compound in a vicinity of the cathode, and to oxidize water and thus produce oxygen in a vicinity of the anode;   stopping the current supply from the power supply and the supply of the carbon dioxide and the electrolytic solution, based on request criteria of reduction performance of the electrolysis cell, and supplying a rinse solution to at least one of the solution supply flow path and the carbon dioxide supply flow path of the electrolysis cell; and   measuring an electric conductivity of the rinse solution passed through the electrolysis cell by using a first electric conductivity meter provided on a discharge port side from the electrolysis cell of at least one of the solution supply flow path and the carbon dioxide supply flow path, and stopping the supply of the rinse solution based on a request criterion of the electric conductivity.   
     
     
         10 . The method according to  claim 9 , wherein
 the supply of the rinse solution is stopped when at least one of a value of the electric conductivity of the rinse solution measured by the first electric conductivity meter and a time change in the electric conductivity is equal to or less than a request criterion.   
     
     
         11 . The method according to  claim 9 , wherein:
 an electric conductivity of the rinse solution is measured by a second electric conductivity meter provided on an inflow port side to the electrolysis cell of at least one of the solution supply flow path and the carbon dioxide supply flow path; and   the supply of the rinse solution is stopped when a difference between an electric conductivity of the rinse solution measured by the second electric conductivity meter and an electric conductivity of the rinse solution measured by the first electric conductivity meter is equal to or less than a request criterion.   
     
     
         12 . The method according to  claim 9 , wherein
 the current supply from the power supply and the supply of the carbon dioxide and the electrolytic solution are stopped when reduction performance data including at least one selected from a cell voltage, a cell current, a cathode potential, and an anode potential of the electrolysis cell, a production amount of a reduction product caused by the cathode, and a product proportion in the reduction product is collected and the reduction performance data is equal to or less than a request criterion.   
     
     
         13 . The method according to  claim 9 , wherein
 a concentration of the electrolytic solution in the solution supply flow path which supplies the electrolytic solution to the anode is measured, and a gas flow rate in the carbon dioxide supply flow path is measured; and   the current supply from the power supply and the supply of the carbon dioxide and the electrolytic solution are stopped when a time integral value of a product of the concentration of the electrolytic solution and the gas flow rate from a reference time is equal to or less than a request criterion, the reference time being the one shorter between elapsed times from after starting a device start-up and from after stopping previous refresh operation.   
     
     
         14 . The method according to  claim 9 , wherein
 the current supply from the power supply and the supply of the carbon dioxide and the electrolytic solution are stopped when an impedance of the electrolysis cell is measured and the impedance is equal to or less than a request criterion.